What is causing the reduced drug-placebo difference in recent schizophrenia clinical trials and what can be done about it?

Add-on mirtazapine improves depressive symptoms in schizophrenia: a double-blind randomized placebo-controlled study with an open-label extension phase

Depression is common in schizophrenia and worsens its course. The role of antidepressants for schizophrenic depression remains unclear. In this study, the efficacy of add-on mirtazapine on depression in schizophrenia was explored in a subsidiary arm of a recent randomized controlled trial. Patients (n = 41) with chronic but stable schizophrenia and inadequate response to stable doses of different first-generation antipsychotics were treated with add-on mirtazapine 30 mg or placebo during a 6-week double-blind phase and with open-label add-on mirtazapine during a 6-week extension phase. Efficacy measures were the Calgary Depression Scale for Schizophrenia (CDSS) and the Positive and Negative Syndrome Scale depression item. During the double-blind phase, both measures' scores decreased significantly in the mirtazapine group but not in the placebo group (for the CDSS, 52.0% vs 19.6%, respectively). During the open‐label phase, both groups demonstrated significant improvements. In between‐group comparison, a trend favoring mirtazapine did not reach statistical significance. The changes in the CDSS correlated positively with those in the Positive and Negative Syndrome Scale negative, positive and total (sub)scales for mirtazapine‐treated patients during the double‐blind phase. Depressed patients with schizophrenia may benefit from mirtazapine–first‐generation antipsychotics combination, with no increased risk for psychosis. However, more studies are needed.

Placebo response in clinical trials with schizophrenia patients

PURPOSE OF REVIEW

The magnitude of placebo response is an important factor in the outcome of clinical trials, in that excessive placebo response can obscure true drug-placebo differences. There is ample evidence of the impact of elevated placebo response in trials of major depression, but less intensive research has been done in the area of schizophrenia. We present a current review of placebo response in clinical trials of schizophrenia.

RECENT FINDINGS

The existing evidence suggests that placebo response in schizophrenia trials may be similar in magnitude, quality, and impact to that observed in depression trials, and has similarly increased over the past several years. We discuss factors influencing excessive placebo response during the conduct of clinical trials and how they may be managed to help minimize placebo response.

SUMMARY

There does not appear to be any single major factor contributing to the high levels of placebo response in schizophrenia clinical trials; therefore, a multipronged approach to minimizing excessive placebo response or its impact is recommended.

Randomized controlled trials in schizophrenia: opportunities, limitations, and trial design alternatives

State-of-the art clinical trial design and methodology are enormously important for the advancement of the field. In contrast, the critical relevance of trial conduct and implementation have only more recently been the focus of discussion and research. Although randomized controlled trials are generally considered the gold standard for the assessment of pharmacologic and nonpharmacologic interventions in medicine, trials are vulnerable to complications and influences that can seriously compromise their success. Like interventions, trial design and conduct are also contextual. They need to be individualized and adapted to a number of relevant variables, such as setting, population, illness phase, interventions, patient and rater expectations and biases, and the overall aims of the investigation. While this means that there is no unified approach possible, certain general principles and guidelines require careful consideration. Knowledge of basic solutions and alternatives, and the recognition of the complex challenges that need to be addressed proactively can help to minimize unwanted outcomes, including trial failure and uninformative or falsely negative outcomes. Moreover, novel design alternatives need to be explored that target sample enrichment according to the study question and enhancement of precision in the measurement of relevant outcomes. We propose two novel design strategies that take advantage of the recently validated early antipsychotic response paradigm (that has also been observed with antidepressants and mood stabilizers). In the "early responder randomized discontinuation design" all patients are assigned to the active drug, and only those who had at least a minimal response at 2 weeks are enrolled in a double-blind, placebo-controlled discontinuation trial, enriching the placebo controlled trial portion with true drug responders. In the mirror image "early nonresponder randomized dose increase or augmentation design," early nonresponders at 2 weeks are assigned to staying on the medication or going either to a higher dose or an augmentation agent. It is hoped that through increased attention to the issues raised in this article and further refinement of trial methodology and conduct, the field will make much needed additional progress in the prevention and treatment of schizophrenia.

The Use of Placebo-Controlled Clinical Trials for the Approval of Psychiatric Drugs: Part II-Ethical Considerations Related to the Individual Participant

This is Part 2 of a two-part series on the ethical issues surrounding the use of placebo arms in clinical trials for psychiatric drugs. Part 1 discussed the ethical argument from a statistical, population-based perspective. Part 2 explores the ethical issues of placebo-controlled studies as they relate to individual psychiatric patients who may participate in them. Many patients who are candidates for psychiatric clinical trials would receive poor treatment for their mental illness under standard treatment conditions. Industry-sponsored clinical trials often provide treatment resources otherwise not available to patients at a more intense level of care than the local standard. Moreover, study design features, such as those developed at University of California, San Diego (presented herein), can mitigate the risks of placebo arms. With this in mind, clinical trials represent an ethical option for many patients with chronic mental illness.